Communicating in the Blink of an Eye How we represent bits, numbers, letters? Communicating in the Blink of an Eye Lawrence Snyder University of Washington, Seattle © Lawrence Snyder 2004

A Quick Comment on Processing We have written two kinds of Processing programs – static, which only draw a picture dynamic, which keep drawing a picture click What’s The Difference? 8/7/2018 © 2010 Lawrence Snyder, CSE

A Curious Story… The Diving Bell and the Butterfly Jean-Dominique Bauby 8/7/2018 © 2010 Lawrence Snyder, CSE

Asking Yes/No Questions A protocol for Yes/No questions One blink == Yes Two blinks == No PandA implies that this is not the fewest number of blinks … really? 8/7/2018 © 2010 Lawrence Snyder, CSE

Asking Letters In English ETAOINSHRDLU… 8/7/2018 © 2010 Lawrence Snyder, CSE

Compare Two Orderings How many questions to encode: Plus ça change, plus c'est la même chose? Asking in Frequency Order: ESARINTULOMDPCFBVHGJQZYXKW 9 12 8/7/2018 © 2010 Lawrence Snyder, CSE

Compare Two Orderings How many questions to encode: Plus ça change, plus c'est la même chose? Asking in Frequency Order: ESARINTULOMDPCFBVHGJQZYXKW Asking in Alphabetical Order: ABCDEFGHIJKLMNOPQRSTUVWXYZ 12 16 8/7/2018 © 2010 Lawrence Snyder, CSE

Compare Two Orderings How many questions to encode: Plus ça change, plus c'est la même chose? Asking in Frequency Order: 247 ESARINTULOMDPCFBVHGJQZYXKW Asking in Alphabetical Order: 324 ABCDEFGHIJKLMNOPQRSTUVWXYZ 8/7/2018 © 2010 Lawrence Snyder, CSE

An Algorithm Spelling by going through the letters is an algorithm Going through the letters in frequency order is a program (also, an algorithm but with the order specified to a particular case, i.e. FR) The nurses didn’t look this up in a book … they invented it to make their work easier; they were thinking computationally, though they probably didn’t know it 8/7/2018 © 2010 Lawrence Snyder, CSE

Bits PandA is a binary representation because it uses 2 patterns Bit -- it’s a contraction for “binary digit” -- a position in space/time capable of being set and detected in 2 patterns Sherlock Holmes’s Mystery of Silver Blaze -- a popular example where “absent” gives information … the dog didn’t bark, that is the phenomenon wasn’t detected 8/7/2018 © 2010 Lawrence Snyder, CSE

Bytes A byte is eight bits treated as a unit Adopted by IBM in 1960s A standard measure ever since Bytes encode the Latin alphabet using ASCII -- the American Standard Code for Information Interchange 0101 0101 0101 0111 8/7/2018 © 2010 Lawrence Snyder, CSE

ASCII 0100 0011 0101 0011 0101 0000 0100 1000|0111 0101|0111 0011|0110 1011|0110 1001|0110 0101|0111 0011|0010 0001 8/7/2018 © 2010 Lawrence Snyder, CSE

UTF-8 Uniform Transformation Format for bytes (UTF-8) is universal … all characters have a place: 1,2,3,4 B 8/7/2018 © 2010 Lawrence Snyder, CSE

Encoding Information Bits and bytes encode the information, but that’s not all Tags encode format and some structure in word processors Tags encode format and some structure in HTML In the Oxford English Dictionary tags encode structure and some formatting Tags are one form of meta-data: meta-data is information about information 8/7/2018 © 2010 Lawrence Snyder, CSE

OED Entry For Byte -- Metadata byte (baIt). Computers. [Arbitrary, prob. influenced by bit sb.4 and bite sb.] A group of eight consecutive bits operated on as a unit in a computer. 1964 Blaauw & Brooks in IBM Systems Jrnl. III. 122 An 8-bit unit of information is fundamental to most of the formats [of the System/360]. A consecutive group of n such units constitutes a field of length n. Fixed-length fields of length one, two, four, and eight are termed bytes, halfwords, words, and double words respectively. 1964 IBM Jrnl. Res. & Developm. VIII. 97/1 When a byte of data appears from an I/O device, the CPU is seized, dumped, used and restored. 1967 P. A. Stark Digital Computer Programming xix. 351 The normal operations in fixed point are done on four bytes at a time. 1968 Dataweek 24 Jan. 1/1 Tape reading and writing is at from 34,160 to 192,000 bytes per second. <e><hg><hw>byte</hw> <pr><ph>baIt</ph></pr></hg>. <la>Computers</la>. <etym>Arbitrary, prob. influenced by <xr><x>bit</x></xr> <ps>n.<hm>4</hm></ps>and <xr><x>bite</x> <ps>n.</ps> </xr></etym> <s4>A group of eight consecutive bits operated on as a unit in a computer.</s4> <qp><q><qd>1964</qd><a>Blaauw</a> &amp. <a>Brooks</a> <bib>in</bib> <w>IBM Systems Jrnl.</w> <lc>III. 122</lc> <qt>An 8-bit unit of information is fundamental to most of the formats <ed>of the System/360</ed>.&es.A consecutive group of <i>n</i> such units constitutes a field of length <i>n</i>.&es.Fixed-length fields of length one, two, four, and eight are termed bytes, halfwords, words, and double words respectively. </qt></q><q><qd>1964</qd> <w>IBM Jrnl. Res. &amp. Developm.</w> <lc>VIII. 97/1</lc> <qt>When a byte of data appears from an I/O device, the CPU is seized, dumped, used and restored.</qt></q> <q><qd>1967</qd> <a>P. A. Stark</a> <w>Digital Computer Programming</w> <lc>xix. 351</lc> <qt>The normal operations in fixed point are done on four bytes at a time.</qt></q><q><qd>1968</qd> <w>Dataweek</w> <lc>24 Jan. 1/1</lc> <qt>Tape reading and writing is at from 34,160 to 192,000 bytes per second.</qt></q></qp></e> 8/7/2018 © 2010 Lawrence Snyder, CSE

Representing Information This week we have seen … Bits encode numbers using the binary representation 11 1110 0111 Bits encode letters using ASCII for North American and Western European languages This suggests an principle we will soon argue: All information can be represented with bits 8/7/2018 © 2010 Lawrence Snyder, CSE

Summary Computers join physical & logical domains so physical devices do our logical work Symbols represent things 1-to-1: 0, 1 Create symbols by grouping patterns: 0101 0111 Bit, a place where 2 patterns set/detect ASCII is a byte encoding of Latin abet In addition to content, encode structure: meta 8/7/2018 © 2010 Lawrence Snyder, CSE

Assignment 8/7/2018 © 2010 Lawrence Snyder, CSE